Timing unit for centrifugal switches



Jan. 28, 1947.y E, w, RlcKMEYER 2,414,836

TIIING UNIT FOR CENTRIFUGAL SWITCHES Filed July 20,` -1944 .Figs

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INVENTOR n ERNST' WALTER R/cKMEYER BY MZ@ Patented Jan. 28, 1947 TIMING UNIT FOR CENTRIFUGAL SWITCHES Ernst Walter Rickmeyer, Elmhurst, Ill., assignor to Jefferson Electric Company, Bellwood, Ill., a corporation of Illinois Application July 20, 1944, Serial o. 545,747

(Cl. 20G-80) 10 Claims.

1 This invention relates to switches of the character described in my previously filed applications, Serial No. 530,123, led April 8, 1944, and Serial No. 534,446, filed May 6, 1944. In these devices, particularly where the switch is .used to open-a circuit, it is often essential that a very,`

low resistance path exist between the shell and the center contact. One purpose of this invention is to improve the switch construction whereby to insure a 4good low resistance connection through the mercury by utilizing a surface ma- .terial engaging the mercury that will amalgamate somewhat with the mercury. This amalgamation should be at such a rate as not to adversely affect the flow characteristics of the mercury. It must also be coniined to the interior of the switch so that the sealing of the switch will not be destroyed.

It is also an object o1' the present invention to provide an improved switch construction whereby the necessity of welding the oriiice 'containing element in place in order to prevent leakage from one chamber of the switch to the other is avoided. y

Other and more detailed objects and advantages of the invention will appear more fully as the description proceeds, reference being had to the accompanying drawing wherein a preferred form of the invention is shown. It is to be understood however that the drawing and description are illustrative only and are not to be taken as limiting the invention except insofar as it is limited by the claims.

Fig. 1 is a longitudinal sectional view through a switch` embodying my invention;

Fig. 2 is a. sectional view taken on the line 2--2 of Fig. 1;

Fig. 3 is a sectional view similar to Fig. 1 showing a modified form of the switch and illustrating the mounting of the wiring terminals thereon;

Fig. 4 is an end view of the construction shown in Fig. 3; and

Fig. 5 is a longitudinal sectional view through a. switch embodying further modlcations oi' the invention.

Referring new in detail to the drawing, the present invention is embodied in a switch of the character generally described in the previous applications above referred to. In certain forms of the invention a sintered metal type of restriction member is shown, while in other forms of the invention the type of restriction member is a fibrous one. In all cases an orice containing disk is utilized to support the restriction member. The switch constructions shown herein are of the type wherein a shell is divided by the orifice containing disk and the restriction member into two chambers, one of which contains a center Contact member. The switch is intended. to be used on a rotating device whereby centrifugal force will force a body of mercury that is contained in one of the chambers into the other chamber to either make or break a circuit connection between the shell and the center contact.

In Fig. '1 of the drawing a shell I0 is formed of steel or other suitable material. rl'he shell has a restricted end portion Ii which provides a. seat at i2 for an orice containing disk I3. The disk I3 has an orifice I4 of prdetermined cross section area therein. The disk I3 provides a partition separating the interior of the shell into two chambers I5 and I8. The shell also has a center contact I1 extending into it from one end thereof, the center contact being mounted upon an insulating washer assembly consisting of two washers I8 and I9. A terminal 20 is secured with the insulating washers to the center contact by spinning over the outer end 2| of the center contact.

In this form of the invention I utilize a powdered sintered metal wafer 22 as a restriction member to limit the i'low of mercury from the chamber i6 to the chamber I5 when pressure is applied by setting up a centrifugal force axially oi the shell due to rotation of the shell in the manner described in my previous applications. The sintered metal wafer 22 is seated in a recess 23 provided in the disk I3 and is held in this recess by turning over a portion of the metal around the periphery of the recess as indicated at 2li. v

It is well known that steel alone is a poor electrical contact. Likewise mercury in contacting steel does not make a very good electrical connection. In order to overcome this dilculty I provide a sleeve 2'5 of copper within the shell Iii. This copper sleeve serves as a supporting means for the insulating washer I8 and furthermore as a spacer between the disk i3 and the washer I8 to determine the spacing between the Contact il and the restriction member 22. The copper of the sleeve 25 will amalgamate slowly with the mercury but the rate of amalgamation is such that it will not affect the characteristics of the mercury adversely during the time the switch must be in use. This construction is particularly applicable to a one-time operation switch which will be operated within a reasonable time after it is produced. In order further to establish a means of producing better contact between the shell and the sleeve 25 the sleeve25 is driven into the shell and before being driven into the shell is coated with mercury on its surface, thus providing a copper mercury amalgam surface that will provide an extremely uniform condition of engagement between the copper sleeve and the steel shell. The center contact l1 is desirably of a material having good conducting characteristics. In the form shown in Figs. 1 and 2 the center contact il is of stainless steel. However in the other forms of the invention a center contact is provided that has better characteristics of conductivity and of contact with the mercury so as to get a lower contact resistance.

Referring now to Figs. 3 and 4, in this form of the invention a center contact 21,' also of stainless steel, is provided with a copper ring 28 that is pressed onto a reduced extension 29 of the center contact. In this form of the invention added advantages of the copper in establishing a low resistance contact with the mercury are obtained.

In this form of the device theA orifice is provided by utilizing an orice disk 3l!v having an orice 3| therein. Over this orifice is placed a lter assembly which comprises a layer 32 of blotting paper between two layers 33 and 34 of linen. A copper cup 35 is seated on the filter assembly. This cup has an aperture 36 in the bottom thereof. which is somewhat larger than the orice 3l. The shell construction is essentially the same as in Fig. l but it will be noted that in Fig. 3 one chamber 31 is like the chamber I 5 of `Fig. 1 while the other chamber 38 is entirely within the cap 35.

The center contact 2'1 may be secured in the same fashion as in Fig. 1, utilizing two insulating washers 39 and 40. As shown, the shell l is shouldered at 4| by reducing the thickness of the shell wall and the insulating washer 39 is secured in place by spinning over the outer edge 42 of the cup.

A terminal 20 just like the terminal 20 is provided for the center contact. Also, Fig. 3 shows the shell terminal comprising a ring 3 spot welded onto the reduced portion Il of the shell and povided with an extending strip 5 which is oiset at 45 and then extended beyond the end of the shell so as to be properly positioned with respect to the terminal 25'. Fig. 4 shows the position of the terminals with respect to each other and with respect to the shell.

It has been found that polystyrene washers are not satisfactory under certain conditions of extreme temperatures. At extremely low temperatures they shrink so much as to destroy the seal. In order to overcome this diiculty the type of seal shown in Fig. is employed. This type of seal utilizes a phenolic resin washer 46 and faces the outer surface of the washer with a layer 41 of neoprene. A smaller washer 48 of phenolicresin is then placed between the neoprene facing and the terminal 20.

In the form of the invention shown in Fig. 5 the orice assembly is the same as in Fig. 3. However, the center contact construction is changed to provide a center contact 69 for getting better contact with the mercury. The center contact 59 comprises a Monel metal core with a copper sleeve 50 pressed thereon. It was found that we could not unite the copper sleeve with stainless steel but it can be united with a Monel metal core in such fashion as to have a very low resistance. In this type of contact the copper 4 surface is entirely within the shell. The insulating washer 6 has a center opening that is kthat the nature and advantages of my invention will be apparent to those skilled in this art.

Having thus described my invention, what I claim as new and desire to secure by Letters Pat-` ent is:

1. In a switch of the character described, a tubular shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of the shell and insulating the contact from 'the shell, a partition spaced from said contact in said shell, said partition including means providing a restricted orice which passes mercury underhigh pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., incident to handling, a cup having an inner surface of high aiilnity for the mercury, said cup being seated in the shell around the center contact, and mercury in the cup.

2. In a switch of the character described, a tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of theshell and insulating the contact from the shell, a partition spaced from said contact in said shell, said partition including means providing a restricted orice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., incident to handling, said center contact comprising a body of metal having a low aiiinity for mercury, and a metal having a strong tendency to amalgamate with mercury covering a portion of said body of metal.

3. In a switch of the character described, a

tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of the shell and insulating the contact from the shell, a partition spaced from said contactin said shell, said partition including means providing a restricted orice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., incident to handling, said center contact comprising a body of Monel metal at least partially covered with a metal having a strong tendency to amalgamate with mercury.

4. In a switch of the character described, a tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of the shell and insulating the Contact from the shell, a partition spaced from said contact in said shell, said partition including means providing a restricted orice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., incident to handling, said center contact comprising a body of Monel metal and a sleeve of copper encircling the Monel body and united therewith.

5. In a switch of the character described, a tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of the shell and insulating the contact from the shell, a partition spaced from said contact in said shell, said partition including means providing a restricted orifice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., incident to handling, and a cup having an inner surface of high affinity for the mercury, said cup being seated in the shell around the center contact, said center contact comprising a body of metal having a. low affinity for mercury, and a metal having a strong tendency to amalgamate with mercury covering a portion of said body of metal.

6. In a switch of the character described, a tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of the shell and insulating the contact from theshell, a partition spaced from said contact in said shell, said partition including means providing a restricted orifice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc.,

incident to handling, said center contact comprising a body of Monel metal and a sleeve of copper encircling the Monel body and united therewith, and a cup having an inner surface of high aiiinity for the mercury, said cup being seated in the shell around the center contact.

7. In a switch of the character described, a tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said` contact on said end of `the shell and insulating the Contact from the shell, a partition spaced from said contact in said shell, said partition including means providing a restricted orifice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., incident to handling, and a cup having an Ainner surface of high aflinity for the mercury, said cup being seated in the shell around the center ccntact, said center contact having a copper band thereon.

v8. In a switch of the character described, a tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of the shell and insulating the contact from the shell, a partition spaced from said contact in said shell, said partition including means providing a restricted orifice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., 1ncident to handling, said mounting and insulating means comprising phenolic resin insulation Washers and a layer of rubber, the rubber being on the outer surface of the innermost washer.

9. In a switch of the character described, a tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of the shell and insulating the contact from the shell, a partition spaced from said contact in said shell, said partition including means providing a restricted orifice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., in-` cident to handling, and a cuphaving an inner surface of high affinity for the mercury, said cup being seated in the shell around the center contact, the outer surface of said cup being mercury coated whereby to establish a low resistance joint with theshell.

10. In a switch of the character described, a tubular shell, mercury in the shell, a center contact extending into said shell at one end thereof, means mounting said contact on said end of the shell and insulating the contact from the shell, a partition spaced from said contact in said shell, said partition including means providing a restricted orifice which passes mercury under high pressure but prevents passage of mercury at atmospheric pressure under jolts, impacts, etc., incident to handling, a copper lining in the shell and acopper sleeve on the center contact.

ERNST WALTER RIC'IKMEYER. 

